1. Field of the Invention
This invention relates to a vehicle height adjusting apparatus for adjusting the height of a vehicle based on an operating signal from a controller.
2. Description of the Related Art
A heavy duty truck or the like adopts an air spring as a spring of a suspension. A vehicle height (the height of a vehicle body frame from an axle) can be adjusted by controlling compressed air supplied to and discharged from the air spring. Concretely, the vehicle height can be raised by supplying compressed air to the air spring to increase the spring length. Conversely, the vehicle height can be lowered by discharging compressed air from the air spring to decrease the spring length. That is, a vehicle height adjusting apparatus is composed of the air spring, and a control mechanism for supplying compressed air to, and discharging compressed air from, the air spring. Since a truck or the like has such a vehicle height adjusting apparatus, the vehicle height can be controlled to the desired height during loading or unloading of cargo.
A conventional vehicle height adjusting apparatus provided in a truck will be described with reference to FIG. 11. In a truck 1, as shown in FIG. 11, a front axle air suspension portion 2 is disposed on a front axle, and a rear axle air suspension portion 3 is disposed on a rear axle. Under the control of an air suspension ECU (electronic control unit) 4, compressed air is supplied to and discharged from the air spring of each of the air suspension portions 2 and 3. An in-cab socket 5 is disposed within a cab of the truck 1, and a frame rear end socket 6 is disposed at the rear end of a truck frame.
A remote control 10 is a wired remote control. A connecting cable 12 is led from a remote control body 11 of the remote control 10, and a remote control socket 13 is connected to the front end of the connecting cable 12. In performing vehicle height adjustment, the remote control socket 13 is connected to one of the in-cab socket 5 and the frame rear end socket 6.
The remote control body 11, as shown, for example, in FIG. 12, is provided with switches, including a front axle selection switch SW1, a rear axle selection switch SW2, a first memory switch SW3, a second memory switch SW4, a neutral switch SW5, a raising switch SW6, a lowering switch SW7, and a stop switch SW8. When the selection switch SW1 or SW2 is pushed (i.e., with one push), an ON-state is produced. When the selection switch SW1 or SW2 is pushed again (i.e., with one push), the switch returns to an OFF-state. That is, the selection switches SW1 and SW2 each alternately repeat the ON-state and the OFF-state with one push.
The remote control body 11 is also provided with a front axle lamp L1 and a rear axle lamp L2. The front axle lamp L1 lights when the front axle selection switch SW1 is ON, and goes out when the front axle selection switch SW1 is OFF. The rear axle lamp L2 lights when the rear axle selection switch SW2 is ON, and goes out when the rear axle selection switch SW2 is OFF.
When the switches SW1 to SW8 are operated while the remote control socket 13 of the remote control 10 remains connected to one of the in-cab socket 5 and the frame rear end socket 6, the lengths of the air springs of the air suspension portions 2 and 3 are adjusted, in the manner described below, under the control of the air suspension ECU 4 to carry out vehicle height adjustment.
(1) At the push of the raising switch SW6 when the front axle selection switch SW1 is ON, compressed air is supplied to the air spring of the front axle air suspension portion 2 while the raising switch SW6 keeps pushed, whereby the vehicle height on the front axle side is raised.(2) At the push of the lowering switch SW7 when the front axle selection switch SW1 is ON, compressed air is discharged from the air spring of the front axle air suspension portion 2 while the lowering switch SW7 keeps pushed, whereby the vehicle height on the front axle side is lowered.(3) At the push of the first memory switch SW3 when the front axle selection switch SW1 is ON, control for supplying and discharging compressed air to and from the air springs of the front axle air suspension portion 2 and the rear axle air suspension portion 3 is exercised so that the vehicle heights at the front and rear axles are raised or lowered until they reach a first vehicle height position which has been stored beforehand.(4) At the push of the second memory switch SW4 when the front axle selection switch SW1 is ON, control for supplying and discharging compressed air to and from the air springs of the front axle air suspension portion 2 and the rear axle air suspension portion 3 is exercised so that the vehicle heights at the front and rear axles are raised or lowered until they reach a second vehicle height position which has been stored beforehand.(5) At the push of the neutral switch SW5 when the front axle selection switch SW1 is ON, control for supplying and discharging compressed air to and from the air springs of the front axle air suspension portion 2 and the rear axle air suspension portion 3 is exercised so that the vehicle heights at the front and rear axles are raised or lowered until they reach a neutral. (reference) vehicle height position which has been stored beforehand.(6) At the push of the raising switch SW6 when the rear axle selection switch SW2 is ON, compressed air is supplied to the air spring of the rear axle air suspension portion 3 while the raising switch SW6 keeps pushed, whereby the vehicle height on the rear axle side is raised.(7) At the push of the lowering switch SW7 when the rear axle selection switch SW2 is ON, compressed air is discharged from the air spring of the rear axle air suspension portion 3 while the lowering switch SW7 keeps pushed, whereby the vehicle height on the rear axle side is lowered.(8) At the push of the first memory switch SW3 when the rear axle selection switch SW2 is ON, control for supplying and discharging compressed air to and from the air springs of the front axle air suspension portion 2 and the rear axle air suspension portion 3 is exercised so that the vehicle heights at the front and rear axles are raised or lowered until they reach the prestored first vehicle height position.(9) At the push of the second memory switch SW4 when the rear axle selection switch SW2 is ON, control for supplying and discharging compressed air to and from the air springs of the front axle air suspension portion 2 and the rear axle air suspension portion 3 is exercised so that the vehicle heights at the front and rear axles are raised or lowered until they reach the prestored second vehicle height position.(10) At the push of the neutral switch SW5 when the rear axle selection switch SW2 is ON, control for supplying and discharging compressed air to and from the air springs of the front axle air suspension portion 2 and the rear axle air suspension portion 3 is exercised so that the vehicle heights at the front and rear axles are raised or lowered until they reach the prestored neutral (reference) vehicle height position.(11) At the push of the stop switch SW8 when the vehicle height is being raised or lowered, a raising action or a lowering action is urgently stopped.(12) The front axle selection switch SW1 and the rear axle selection switch SW2 may be simultaneously rendered ON, and the vehicle heights on the front axle side and the rear axle side may be simultaneously raised (the raising switch SW6 may be pushed), or simultaneously lowered (the lowering switch SW7 may be pushed).
An ordinary technology for the vehicle height adjusting apparatus (air suspension control device) installed in the truck or the like is shown, for example, in Japanese Patent Application Laid-Open No. 2002-192928. This Japanese Patent Application Laid-Open No. 2002-192928 discloses a vehicle height adjusting apparatus for making vehicle height adjustment by use of a wired remote control as does that shown in FIGS. 11 and 12.
With the conventional vehicle height adjusting apparatus shown in FIGS. 11 and 12, the remote control 10 is of the wired type, thus giving a narrow operating range. Hence, when the driver of the truck gets off the truck, and operates a fork lift to do loading work for the truck, the driver cannot make vehicle height adjustment of the truck while riding the fork lift. That is, the driver has to get off the fork lift, connect the remote control socket 13 to the in-cab socket 5 or the frame rear end socket 6, and operate the switch of the remote control 10 near the truck 1. Otherwise, the driver cannot make vehicle height adjustment of the truck.
Depending on the operating situation, the driver may have to disconnect the remote control socket 13 of the remote control 10 from one of the in-cab socket 5 and the frame rear end socket 6, and then connect it to the other. This means poor operability.
The present invention has been accomplished in the light of the above-mentioned problems with the earlier technology. It is an object of the invention to provide a vehicle height adjusting apparatus which can make vehicle height adjustment even when the driver is separated from a vehicle (truck or the like), and which is safe and easy-to operate.